Method and apparatus for controlling hole direction and inclination



Nov. 6, 1962 w. E. scHULTz 3,062,303

METHOD AND APPARATUS FOR CONTROLLING HOLE DIRECTION AND INCLINATION Filed March 2l, 1960 FSS ISM-11;: 4o dl0 lOb FIG. 2

|NVENTORZ W. E. SCHULTZ BYz M 7M Q C HIS AGENT United dtates 3 062,303 METHOD AND APPAIKATUS FR CNTRDLLING HOLE DIRECTION AND INCLINATON Wilburn E. Schultz, Midland, Tex., assignor to Shell Oil Company, New York, N.Y., a corporation of Delaware Filed Mar. 21, 1960, Ser. No. 16,262 6 Claims. (Cl. 175-61) `This invention relates to the drilling of wells in earth formations, and pertains more particularly to a method and apparatus for controlling borehole direction and inclination while drilling a well, such for example as an oil or gas well.

Well `boreholes drilled into the earth generally follow a random and crooked course, caused primarily by layers of rock -being tilted at different angles and caused by differences in rock strength from one layer to another. Random, crooked holes are undesirable as they frequently complicate and slow down the drilling operation. For example, if a well is being drilled to a certain depth below the surface where oil, gas, or mineral deposits are suspected, and the surface location for the well is positioned in the favored area, it is desirable to drill a straight vertical hole within reasonable limitations so that the bottom portion of the well will penetrate the zone of interest. In other instances, because of surface topography, shoreline or offshore surface locations, well sites may be positioned such that a directionally controlled deviated hole is drilled to terminate at or pass through an underground zone of interest or target area which may be a long distance away, horizontally as well as vertically, from the surface location. In both examples of drilling wells, that of drilling a reasonably vertical hole and that of drilling a purposely deected hole which is directionally controlled, the natural, random, meandering tendency of drilled holes must be overcome by some means.

In order to drill a reasonably straight vertical well, various alternations in normal drilling operations may be employed. For example, the natural crooked-hole tendencies of drilled holes are often combatted by employing, above the drill bit, a stiff drill collar string having only a small clearance with the borehole wall. Alternatively, stabilizers may be placed in the drill string above the bit more nearly lto center the drill string so as to serve as a fulcrum, with the drill collar string just above the bit acting as a pendulum tending to return the hole to vertical. These methods however are frequently not sufficient -to produce a straight hole, so that it is necessary to reduc-e the weight applied to the drilling bit in an attempt to continue drilling a vertical borehole. Reduced bit weight is generally used where crooked hole is a problem and frequently is successful in controlling hole deviation. Reduction of bit weight however has the inherent drawback of slowing down the rate at which a well is drilled thus resulting in higher drilling costs.

It is therefore a primary object of the present invention to provide a method and apparatus for drilling through earth formations a straight vertical hole within acceptable limitations without having to reduce bit weight and drilling speed.

In order to drill a well having a directionally-controlled inclined bore, whipstocks are employed to deect the hole in the desired direction. The hole inclination may be increased or maintained by use of a more flexible and large clearance drill collar string immediately above the bit, by increased bit weight, or by use of whipstocks. Whipstocks are generally used with varying degrees of success in wells where it is diicult to increase and maintain hole inclination and/ or difficult to control hole di- 3,052,303 Patented Nov. 6, 1962 rection. This method has the inherent drawback that it is necessary to stop drilling operations periodically to deflect the hole by drilling a smaller pilot hole, which must then be reamed to the larger hole size, all of these operations being time consuming and costly.

It is therefore a further object of the present invention to provide a method and apparatus for purposely deviating a full size hole and maintaining the desired direction and inclination while drilling a well through earth formations.

Another object of the present invention is to provide a well drilling guide tool adapted to be positioned in an inclined well borehole by a jarring action applied from the wellhead or surface.

These and other objects of this invention will be understood from the following description taken with reference to the drawings, wherein.

FIGURE l is a diagrammatic view, taken in crosssection, of the apparatus of the present invention adapted to be used for straightening holes and for maintaining as small a hole inclination from vertical as possible when drilling through formations tending to deviate the hole from vertical;

FIGURE 2 is a diagrammatic view, taken in crosssection, of the apparatus of the present invention adapted to be used for deviating holes and for maintaining a large hole inclination from vertical when drilling a directionally controlled well to an underground target area displaced horizontally from the surface Well site;

FIGURE 3 is a View taken along 3 3 of FIGURE 1; and,

FIGURE 4 is a view taken along 4-4 of FIGURE 2.

Referring to FIGURE l, the apparatus of the present invention includes a tubular shaft 10 having shoulder elements 10a and 10b threaded at each end for connection to the tubular drilling string A and drilling bit B. A freely-rotatable annular body member or sleeve 11 of a length less than that of the shaft 10 is positioned around the tubular shaft 10 for limited axial movement thereon so that the sleeve 11 may remain stationary while the shaft lil may be rotated or moved up and down. The circular body sleeve 11 contains a preferably elongated annular chamber in at least its central part, with a transverse wall 12 partitioning the chamber into two individual chambers 13 and 14 (FIGURE 3). Chamber section 13 contains air while chamber section 14 contains mercury 15. The chamber section 14 is preferably only partially filled with mercury 15 so that the mercury 15 is free to flow in the chamber section 14 when a jarring or pounding action is imparted to the body sleeve 11 as it slides axially between stop members or shoulders 10a and 10b at the ends of the shaft 10. A jarring action is obtained by raising or lowering the drill string A rapidly and abruptly stopping. As an aid in moving the annular body sleeve 11 both vertically and/or rotatably on the shaft 10 a circular set of springs 18 is preferably attached to the lower end of the body sleeve 11. The type, construction and number of springs 18 to be used is selected so that the springing action of the long drill string, in addition to the action imparted by the springs 18, is sutiicient to overcome frictional forces between the surfaces of radial bearings 16 and 17 and the body sleeve 11 and/ or shaft 10, to cause vertical movement and thus allow rotational movement of the sleeve 11 relative to the shaft 10. The turbulent movement and weight of the heavy mercury 15 in the chamber section 14 is designed to cause the body sleeve 11 to turn slightly in relation to the shaft 10 to a position such that the chamber section 14 becomes positioned at the low perimeter of an inclined hole after a number of jarring actions. Thus the empty chamber section 13 is then positioned at the high perimeter of the inclined hole.

In the central portion of chamber section 13, a slidable metal shoe 2t) is positioned in a recess 21, preferably dovetailed top and bottom, as at 21a, and which is isolated from air chamber section 13. The metal shoe 2li is attached to the body sleeve 11 in the recess by means of springs 22 which normally tend to hold the shoe 2G in an inward direction. Fluid ports 23 through the wall of the body sleeve 11 in the back portion of the recess Z1 permit entry of Huid to force the shoe 2t) outwardly and against the high perimeter of a borehole. Fluid ports 24 through the wall of the shaft 1@ permit luid circulated through the drill string to enter the annular space between radial bearings 16 and 17 and thus actuate the shoe 20. Radial bearings 16 and 17 may be fluted slightly on their inner surface to allow a small leakage of tluid for purposes of lubricating the bearing surfaces to reduce wear. Slightly iluted bearings still form seals, between the shaft and sleeve 11, sufficient so that fluid pressure forces the shoe 20 outwardly.

After the apparatus of ythe present invention has been run to the bottom of an inclined hole and the drill string A has been jarred up and down a number of times to position the mercury-containing chamber section 14 to the low perimeter of the inclined hole, uid circulation is established in a normal manner down through the drill string A and bit B. The fluid pressure drop across the bit fluid openings, which can be regulated by the pump pressure or fluid circulation rate, causes the metal shoe 20 to slide outward and push against the high perimeter of the borehole traversing earth formations. This force, which is perpendicular to the center line of the hole, is transmitted through the radial bearings 16 and 17 to the shaft 10 which is rigidly connected to the drilling bit. With the shoe 20 forced against the hole by the circulating fluid, the drill string is preferably reciprocated up and down a few feet in either direction to groove the wall of the hole slightly with the surface of the shoe 20 so as to reduce the tendency of the circular body sleeve 11 to turn when drilling is started.

Drilling is then again resumed by rotating the drill string A and applying weight on the bit B in the usual manner. The circular body sleeve 11 and hydraulically actuated shoe 20 do not turn but remain in essentially one plane, sliding or being pushed down the hole as the bit drills ahead. The metal shoulder 10a at the top of the shaft 10 rotates against the top of the sleeve 11 as the sleeve 11 is pushed or slides down the hole. The force from the metal shoe 20 acting perpendicular to the center line of the hole olf-sets the natural tendency of the t hole to deviate. A thrust bearing 25, such for example as a grooved wear ring, is preferably provided between the top of the sleeve 11 and shoulder 10a. Another bearing 26 may be positioned on the lower shoulder 10b, preferably below springs 18.

Re-positioning of the sleeve 11 can be accomplished at any time by stopping fluid circulation which allows the shoe 20 to be retracted, jarring the drill string A up and down as described previously, re-starting fluid circulation, and then rotating the drill string and drilling ahead once again.

Referring to FIGURE 2, the apparatus of the present invention is the same as previously described for FIGURE l with the exception that the mercury is put into chamber 13 on the opposite side of the sleeve 11, with the chamber 14 being the air-containing chamber, the reverse of that illustrated in FIGURE 1. Thus, the shoe is recessed in the mercury-containing chamber section 13 rather than the air chamber section 14. The apparatus is actuated in the same manner as described previously, but the opposite position of the mercury 15 allows the apparatus to be used purposely to deviate holes from vertical rather than to straighten holes toward the vertical.

Either form of the apparatus of the present invention may be provided with a shear plug 40. This use of a shear plug allows the shoe 26 to be oriented, in a manner well known to the art, such that the horizontally-projected direction of the hole may be changed as desired. After the present invention has been run to the bottom of a hole and the shoe 2) has been oriented in the desired horizontal direction by turning the drill string from the surface, fluid circulation is established through the drill string and bit. The uid pressure causes the metal shoe 26 to slide outward to push against the wall of the hole. This force, which is perpendicular to the center line of the hole, acts to cause the bit to drill in the desired direction. With the shoe 2@ forced against the hole while circulating fluid, the drill string is reciprocated up and down a few feet in either direction to shear the shear plug fit) and to groove the wall of the hole slightly with the surface of the shoe 20 to reduce the tendency of the circular body sleeve 11 to turn when drilling is started. Drilling is then commenced by rotating the drill string and applying weight on the bit in the usual manner. The circular body sleeve 11 and hydraulically-actuated shoe 20 do not turn but remain essentially in one plane, sliding or being pushed down the hole as the bit drills ahead.

After drilling for some distance, say 30 feet, in the oriented direction, it is necessary to stop fluid circulation in order to add an additional length of drill pipe to the drilling string. Following this operation the apparatus cannot be reoriented in the horizontal plane unless it is pulled out of the hole and a new shear plug 40 inserted. However, without pulling the apparatus out of the hole, it is adapted to control hole inclination in the vertical plane by the methods described previously with reference to FIGURES 1 and 2.

I claim as my invention:

1. A method of changing during drilling operations the direction of a well which is inclined to the vertical, said method comprising inserting and rotatably mounting in a drill string above a drill bit an eccentrically- Weighted tool adapted to expand an element radially against the wall of said well, placing said element in pressure communication with `the interior of said drill string, lowering said drill string and tool to substantially the bottom of said well, reciprocating the drill string from the surface with sun'icient force to jar the tool causing it to turn about the drill string axis to a desired position, applying fluid pressure through said drill string to expand radially against the well wall the cxpandible element of said rotatably mounted tool to force the tool to one side of the well, and subsequently rotating said drill string and bit within said Well to resume drilling operations.

2. A method of changing during drilling operations the `direction of a well which is inclined to the vertical, said method comprising inserting and rotatably mounting in a drill string above a drill bit an eccentrically-weighted tool adapted to expand an element radially against the wall of said well, placing said element on the more heavily weighted side of said tool and in pressure communication with the interior of said drill string lowering said drill string and tool to substant-ially the bottom of said well, reciprocating the drill string from the surface with suicient force to jar the eccentrically-weighted tool causing it to turn about the drill string axis to a position where the predominant weight of the tool is positioned on the low side of said inclined well, applying fluid pressure through said drill string to expand radially against the low side of the well the expandible element of said rotatably mounted tool, and subsequently rotating said drill string and bit within said well to resume drilling operations.

3. A method of changing during drilling operations the direction of a well which is inclined to the vertical, said method comprising inserting rotatably mounting in a drill string above a drill bit an eccentrically-weighted tool adapted to expand an element radially against the wall of said well, placing said element on the more heavily weighted side of said tool and in pressure cornmunication with the interior of said drill string lowering said drill string and tool to substantially the bottom of said well, reciprocating the drill string from the surface with sufficient force to jar the eccentrically-weighted tool causing it to turn about the drill string axis to a position where the predominant weight of the tool is positioned on the low side of said inclined well, applying uid pressure through said drill string to expand radially against the high side of the well the expandible element of said rotatably mounted tool, and subsequently rotating said drill string and bit within said well to resume drilling operations.

4. A hydraulically-actuatable and jarably-positionable guide tool adapted to be connected into a well-drilling drill string above a drill bit carried vat the lower end thereof, said tool comprising a tubular shaft having outwardly-extending stop elements of enlarged diameter formed at either end thereof, means carried by said shaft for connecting said tubular shaft into a drill string, a freely-rotatable annular elongated sleeve having an annular chamber formed therein, said sleeve having a length less than the distance between the stop elements of said shaft and being mounted for limited axial movement on said shaft, axially-extending wall means within said chamber dividing said chamber into two lluidtight compartments, one of said compartments being filled with air, the other of said compartments having the greater portion thereof filled with mercury, a recessed wall-contacting shoe element slidably-mounted in a recess in one compartment of said sleeve and being radially-extendible therefrom, means normally holding said shoe element in a retracted position within said sleeve, fluid passageways through the wall of said shaft and said sleeve in open communication at all times between the space within the tubular shaft and the space adjacent the inwardlydirected surface of the shoe element, and bearing means carried by and forming a part of said tool between said shaft and said sleeve.

5. A hydraulically-actuatable and jarably-positionable guide tool adapted to be connected into a well-drilling drill string above a drill bit carried at the lower end thereof, said tool comprising a tubular shaft having outwardly-extending shoulder elements of enlarged diameter formed at either end thereof, screw threads carried by said shoulder elements for connecting said tubular shaft into a drill string, a freely-rotatable annular elongated sleeve having an elongated annular chamber formed therein, said sleeve having a length less than the distance between the shoulder elements of said shaft and being mounted for limited axial movement on said shaft, axiallyextending Wall means within said chamber dividing said chamber into two fluidtight compartments, one of said compartments being lled with air, the other of said compartments having the greater portion thereof filled with mercury, a recessed elongated wall-containing shoe element slidably-mounted in a recess in one compartment of said sleeve and being radially-extendible therefrom,

said shoe element bein-g in a vertical plane substantially at right angles to the wall between the compartments of said sleeve, spring means normally holding said shoe element in a retracted position within said sleeve, fluid passageways through the wall of said shaft and said sleeve in open communication at all times between the space within the tubular shaft and the space adjacent the inwardly-directed surface of the shoe element, bearing means carried by and forming a part of said tool between said Ishaft and said sleeve at either end thereof, and compression spring means carried by and forming a part of said tool between the lower end of said sleeve and the shoulder element adjacent thereto.

6. A hydraulically-actuatable and jarably-positionable guide tool adapted to be connected into a well-drilling drill string above a drill bit carried at the lower end thereof, said tool comprising a tubular shaft having outwardly-extending shoulder elements of enlarged diameter formed at either end thereof, screw threads carried by said shoulder elements for connecting said tubular shaft into a drill string, a freely-rotatable annular elongated sleeve having an elongated annular chamber formed therein, said sleeve having a length less than the distance lbetween the shoulder elements of said shaft and being mounted for limited axial movement on said shaft, axially-extending wall means within said chamber dividing said chamber into two fluidtight compartments, one of said compartments being filled with air, the other of said compartments having the greater portion thereof filled with mercury, a recessed elongated Wall-contacting shoe element slidably-mounted in a recess in one compartment of said sleeve and being radially-extending therefrom, said shoe element being in a vertical plane substantially at right angles to the wall between the compartments of said sleeve, spring means normally holding said shoe element in a retracted position within said. sleeve, fluid passageways through the wall of said shaft and said sleeve in open communication at all times between the space within the tubular shaft and the space adjacent the inwardly-directed surface of the shoe element, bearing means carried by and forming a part of said tool between said shaft and said sleeve at either end thereof, thrust bearing means carried by and forming a part of said tool between the top of the sleeve and the shoulder element adjacent thereto, compression spring means carried by and forming a part of said tool between the lower end of said sleeve and the shoulder element adjacent thereto, and shear plug means temporarily connecting said sleeve and said shaft together.

References Cited in the le of this patent UNITED STATES PATENTS 2,043,381 Lane June 9, 1936 2,179,567 Strength Nov. 14, 1939 2,316,409 Downing Apr. 13, 1943 2,329,597 Diehl et al. Sept. 14, 1943 2,382,933 Zublin Aug. 14, 1945 2,509,144 Grable et al. May 23, 1950 2,814,462 De `arnett Nov. 26, 1957 

